Treatment of cancer/inhibition of metastasis

ABSTRACT

Substances and methods are disclosed for reducing or preventing metastatic behaviour in VGSC expressing cancer by the effect of at least reducing the persistent part of the voltage gated sodium channel current without eliminating the transient part. Inhibition of metastatic cell behaviours such as detachability, lateral motility, transverse migration and invasiveness is demonstrated using the known drugs ranolazine and riluzole.

BACKGROUND

This invention relates to the treatment of cancer, and is particularly,but not exclusively, concerned with the treatment of metastatic cancer,such as breast or prostate cancer.

Progression of metastatic cancer, such as breast and prostate cancer, isgenerally considered as comprising five phases, as follows:

-   1. Genesis, namely the initial transformation of a normal cell into    a cancer cell.-   2. Proliferation, namely increase in the number of cancer cells to    form a primary tumour of increasing size.-   3. Switching, during the genesis or proliferation phase, from a    condition in which the cancer cells have no potential for metastatic    behaviour to a condition in which they do.-   4. Detachment of cancer cells from the primary tumour followed by    movement of those detached cells into surrounding regions of tissue    within the same organ towards the circulation system.-   5. Metastasis, namely the movement of the detached cells through the    circulation (blood or lymph) to other organs to create secondary    tumours in those other organs.

A significant change which takes place in the cell and causes the switchin condition at phase 3 above is the expression of functionalvoltage-gated sodium channels (VGSCs). In breast cancer it is the Nav1.5channel which is expressed and in the case of prostate cancer it is theNav1.7 channel. VGSCs may be expressed in neonatal and/or adult form. Inthe case of breast cancer, it is the neonatal form of the Nav1.5 channel(nNav1.5) which is expressed. In the case of prostate cancer, it is notcurrently known which form is expressed. In the absence of suchchannels, the cells do not have the potential for invasion and hencemetastatic behaviour.

In some cases, the genesis phase involves the growth of cancer cellswhich, from the outset, have metastatic potential.

Prior Proposals for Preventing Metastasis

Prior to the present invention, the focus in the field has been to tryto find a treatment for preventing metastasis by one or more of thefollowing:

-   (a) preventing the expression of functional VGSCs;-   (b) completely blocking the activity of functional VGSCs which have    been expressed; or-   (c) killing the cells.

The present invention proposes a different approach.

SUMMARY OF THE INVENTION

-   -   Current flows intermittently through VGSCs, that is to say the        current flows in pulses. It is known that each pulse comprises a        transient (or peak) part which is followed by a low-level DC        part, known as the late or persistent current. It is also known        that appropriate doses of the known drugs ranolazine or riluzole        inhibit the persistent part of the current leaving the transient        part either unaffected or only reduced partially.

Experimental work, more fully described below, carried out in connectionwith this invention has demonstrated that:

-   (i) inhibiting the persistent part of the Nav1.5 and Nav1.7 currents    respectively in breast and prostate cancer inhibits metastatic    behaviour;-   (ii) it is not necessary to inhibit the transient part of these    currents in order to inhibit metastatic behaviour;-   (iii) appropriate doses of ranolazine or riluzole will inhibit    metastatic behaviour without preventing proliferation or destroying    the cells of the tumour; and-   (iv) the inhibiting effects of ranolazine and riluzole on the    persistent part of the current are greater in cells with prior    exposure to hypoxia, which is a condition that occurs in growing    tumours and makes a critical positive contribution to the metastatic    process.

Ranolazine and riluzole are both known for the treatment of cardiacconditions. It is further known that each of them differentially affectsthe magnitude of the transient and persistent parts of the VGSCcurrents, the effect being in a dose-dependent manner. High doses ofthese drugs completely block the VGSC currents. Doses of these, or anyother drug, which would have the effect of completely blocking VGSCcurrents in cardiac tissue would be fatal to the patient because theheart requires these currents in order to carry out its function.

However, in accordance with an aspect of the invention, metastaticbehaviour is inhibited or reduced in cancer by administering ranolazineor riluzole, or another substance, at an appropriate dosage to inhibitor reduce the persistent part of the VGSC current without blocking, orat least without completely blocking, the transient part. Thus,metastasis in cancer may be inhibited or reduced in this way withouthaving to administer doses of drugs which would be fatal.

Riluzole has already been proposed in the treatment of certain cancers,in particular prostate cancer and melanoma. In both cases, it wasproposed that riluzole should be administered in such a way that thecancerous cells are killed.

In accordance with a further aspect of the invention, which will be morefully explained below, riluzole, or ranolazine, is administered at adosage level which will inhibit the persistent part of the VGSC currentwithout blocking or completely blocking the transient part and withoutdirectly causing cell death.

The fact that metastatic behaviour may be inhibited or reduced withoutcausing cell death may be a significant advantage since recent work hassuggested that treating cancer by killing the cells may, at least insome cases, be counter-productive in the sense that whilst there will bea short term benefit, the cancer will nevertheless return andproliferate. Thus, the invention provides the possibility of inhibitingor preventing metastatic behaviour without the potential problems whichmay arise from actually killing the cancer cells.

Metastatic behaviour involves several stages, namely:

-   (a) detachment of cells from the tumour;-   (b) movement of the detached cells into the surrounding tissue;-   (c) movement through that surrounding tissue towards the circulation    system; and-   (d) movement into the circulation system (from which the cells may    exit ultimately to form secondary tumours).

Inhibiting or reducing the activity of the cells in any one or more ofthese stages will therefore contribute to at least a reduction inmetastasis. The effect of drugs on each of these sub-stages can bedetermined, as more fully explained below, by a number of experiments,namely:

-   (a) testing the effect of the drug on the adhesiveness of the cells;-   (b) testing the effect of the drug on the lateral motility of the    cells;-   (c) testing the effect of the drug on the transverse migration of    the cells; and-   (d) testing the effect of the drug on the invasiveness of the cells,    namely the ability of the cells to move through a medium which is    consumed by the cells.

As more fully described below, experiments carried out in connectionwith this invention have shown that administering ranolazine or riluzoleat various dosage levels can increase the adhesiveness of the cellsand/or reduce one or more of the lateral motility, transverse migrationand invasiveness of the cells.

Accordingly, in accordance with another aspect of the invention, acompound, composition or other substance is provided which is used orintended to be used, in an appropriate dose, to inhibit or reduce thepersistent part of the VGSC in metastatic cancer cells whilst leavingthe transient part unaffected or only partially reduced, for inhibitingor reducing metastasis, preferably without directly causing cell death.

The advantages that flow from the invention, at least in certain aspectsor forms, are:

-   (a) that breast and prostate cancer (and other cancers in which    VGSCs are expressed) can be contained so that the patient may be    able to live with such cancer without serious detriment;-   (b) as a result, the need for the patient to undergo aggressive    treatments to destroy the cancerous cells, such as by chemo or    radiotherapy may be avoided;-   (c) if a patient is suspected of having breast or prostate or other    metastatic cancer, immediate treatment with appropriate doses of    ranolazine or riluzole (or other substance with the relevant    properties) can be given to inhibit or prevent metastasis whilst    awaiting the results of definitive tests;-   (d) the dosage necessary to achieve this only has to be high enough    to inhibit the persistent part of the VGSC current;-   (e) therapeutically acceptable doses of ranolazine or riluzole will    achieve the required inhibition of the persistent part of these    currents, whilst leaving the transient part substantially    unaffected; and-   (f) since ranolazine and riluzole have been on the market and    approved for human use for many years, the invention can be put into    clinical use without having to go through all the lengthy testing    for side effects etc.

DETAILED DESCRIPTION

The invention is further described with reference to the accompanyingdrawings and experimental data set out below.

In the drawings:

FIG. 1 is a schematic representation of a timeline for cancerprogression from primary tumorigenesis to formation of secondary tumours(metastases);

FIG. 2 is a schematic illustration of the cellular processes occurringduring cancer initiation and progression to metastasis;

FIG. 3 (a) is a sketch illustrating the current through VGSC's, showingboth the transient and persistent parts of the current and also showingthe current under both normoxic and hypoxic conditions;

FIG. 3 (b) is a sketch illustrating the effect of differingconcentrations of ranolazine on the VGSC current components;

FIG. 3 (c) is a sketch illustrating the effect of differingconcentrations of riluzole on the VGSC current components;

FIG. 4 is a schematic illustration of a cell adhesion measuringapparatus for measuring the adhesion of cells singly;

FIG. 5 is a schematic illustration of apparatus used for measuring thelateral motility of cells; view (a) is a plan view from above of a cellculture dish containing a semi-confluent layer of cells; view (b) is aschematic side sectional view of the plated cells; view (c) is a planview of the plated cells at time t=zero when a scar has been createdthrough the layer of cells, and view (d) is a plan view of the platedcells at a later time (t=24 hours) after the cells have moved and thewound has partially closed;

FIG. 6 is a schematic side sectional view of apparatus used formeasuring the transverse migration of cells;

FIG. 7 is a schematic side sectional view of apparatus used formeasuring the invasiveness of cells;

FIG. 8 is a graph showing the concentration dependent effect of inducedchemical hypoxia on the single-cell adhesion of human metastatic breastcancer MDA-MB-231 cells;

FIG. 9 is a graph showing the dose-dependent effect of ranolazine on thesingle-cell adhesion of MDA-MB-231 cells under normoxia and chemicallyinduced hypoxia;

FIG. 10 is a histogram showing the dose-dependent effects of ranolazineon the lateral motility of MDA-MB-231 cells under normoxia and hypoxia;

FIG. 11 is a histogram showing the dose-dependent effect of ranolazineon the transverse migration of MDA-MB-231 cells under normoxia andhypoxia;

FIG. 12 is a histogram showing the dose-dependent effect of ranolazineon the invasiveness of MDA-MB-231 cells under normoxia and hypoxia;

FIG. 13 is a series of histograms showing the dose-dependent effect ofranolazine on the invasiveness of MDA-MB-231 cells that have beenpre-treated with ranolazine for different durations under hypoxia; view(a) is a histogram showing the effect of 5 μM ranolazine for cellstreated only for 24 hours during the assay (i.e., no pre-treatment);view (b) is a histogram showing the effect of 5 μM ranolazine for cellspre-treated with the drug for 72 hours; view (c) is a histogram showingthe effect of 25 μM ranolazine for cells treated only for 24 hoursduring the assay (i.e., no pre-treatment); view (d) is a histogramshowing the effect of 5 μM ranolazine for cells pre-treated with thedrug for 48 hours, and view (e) is a histogram showing the effect of 5μM ranolazine for cells pre-treated with the drug for 72 hours;

FIG. 14 is a series of histograms showing lack of effect of ranolazineon the growth of MDA-MB-231 cells under normoxia;

FIG. 15 is a histogram showing the lack of effect of ranolazine on theviability of MDA-MB-231 cells under normoxia;

FIG. 16 is a histogram showing the dose-dependent effect of ranolazineon the transverse migration of rat strongly metastatic prostate cancerMat-LyLu cells under normoxia and hypoxia;

FIG. 17 is a histogram showing the dose-dependent effect of ranolazineon the invasiveness of Mat-LyLu cells under normoxia and hypoxia;

FIG. 18 is a histogram showing the lack of effect of ranolazine on theproliferation of Mat-LyLu cells under normoxia and hypoxia;

FIG. 19 is a histogram showing the lack of effect of ranolazine on theviability of Mat-LyLu cells under normoxia and hypoxia;

FIG. 20 is a histogram showing the dose-dependent effect of riluzole onthe lateral motility of MDA-MB-231 cells under normoxia and hypoxia;

FIG. 21 is a histogram showing the dose-dependent effect of riluzole onthe transverse migration of MDA-MB-231 cells under normoxia and hypoxia;

FIG. 22 is a histogram showing the dose-dependent effect of riluzole onthe invasiveness of MDA-MB-231 cells under normoxia and hypoxia;

FIG. 23 is a pair of histograms showing the comparative effect on theinvasiveness of MDA-MB-231 pre-treated with 5 μM riluzole for >72 hoursunder hypoxia; view (a) is a histogram showing the effect of 5 μMriluzole for cells treated only for 24 hours during the assay (i.e., nopre-treatment); view (b) is a histogram showing the effect of 5 μMriluzole for cells pre-treated with the drug for 72 hours;

FIG. 24 is a histogram showing the dose-dependent effect of riluzole onthe growth of MDA-MB-231 cells under normoxia;

FIG. 25 is a histogram showing the dose-dependent effect of riluzole onthe viability of MDA-MB-231 cells under normoxia;

FIG. 26 is a histogram showing the dose-dependent effect of riluzole onthe invasiveness of Mat-LyLu cells under normoxia and hypoxia;

FIG. 27 is a histogram showing the dose-dependent effect of riluzole onthe growth of Mat-LyLu cells under normoxia and hypoxia, and

FIG. 28 is a histogram showing the dose-dependent effect of riluzole onthe viability of Mat-LyLu cells under normoxia and hypoxia.

With reference to FIG. 1, timeline 101 is a representation of threesuccessive phases in the development of a tumour, namely a phase 102prior to the development of cancerous cells, a phase 103 following phase102 during which the genesis of cancer cells takes place and a phase104, following phase 103, during which the cancerous cells proliferateso as to form a growing tumour. The proliferation phase 104 may beginsoon after the genesis phase 103 begins.

It has been established that human breast and human prostate cancercells may initially not include any functional VGSCs and that, unlesssuch channels are expressed in the tumour, the tumour cells will not beinvasive. However, in many such tumours, even though initially there areno VGSC's, at some point functional VGSC's will be expressed. Thistriggers a change to a condition in which the tumour may spread. FIG. 1represents a situation in which initially the cells do not contain anyfunctional VGSC's but at some point in time 105 the expression offunctional VGSC begins. This may occur at any time after commencement ofthe genesis phase 103.

Timeline 106 in FIG. 1 illustrates the phases which arise following time105, when the cancer becomes metastatic.

In the first phase 107 following time 105, metastatic cells detachthemselves from the tumour. Thereafter, in phase 108, they invade andmove through surrounding tissue in the same organ towards thecirculation system, in particular the vascular and/or the lymphaticsystem. In phase 109, the metastatic cells enter the circulation systemwhich may then carry them to other organs in the body, at which they maycause the formation of secondary tumours.

The above phases are pictorially represented in FIG. 2 in whichreference number 200 represents a portion of an organ such as a breastor a prostate. Healthy cells 201 of the breast or prostate are shown assupported on a basement membrane 202 and surrounding a cancerous tumour203, which is assumed to have gone through the genesis phase 103 andinto the proliferation phase 104.

Certain cells 204 of the cancerous tumour 202 are shown as detachingfrom the tumour 203 and passing through a degraded region 202 a of thebasement membrane 202 into adjacent region 205 of the organ containingthe tumour 203, which region may comprise mainly collagen fibres. Cancercells 206, which have become detached from the tumour and have passedthrough the basement membrane 202, are shown passing through the region205 towards a blood vessel 207. A cancerous cell 208 is shown migratingthrough the wall of the blood vessel 207 into the bloodstream 209.

Cells 210, which have already entered the bloodstream, are shown asbeing carried within the bloodstream to a region 211 where cells 212 areshown as having migrated outwardly through the wall of the blood vessel207 towards another organ 213, such as the lymph glands or liver, inwhich they may form a secondary tumour (not shown).

Reference number 214 represents dormant cancerous cells which havesimply settled in or adjacent to the wall of the blood vessel 207.

As more fully explained below, the invention provides a treatment ormeans for preventing or reducing one or more of the metastaticbehaviours of the cancer cells which takes place in the various phasesdescribed. In particular, the invention provides a treatment or meansfor:

-   (a) increasing the adhesiveness of the cells in the tumour so that    they are less likely to detach; and/or-   (b) reducing the motility of the cells which have become detached so    they are less likely to move to and through the basement membrane    into the surrounding tissue; and/or-   (c) reducing the invasiveness of the cells which have entered the    surrounding tissue by reducing their ability to move through that    tissue towards the circulation system; and/or-   (d) reducing the ability of the cells to migrate from that tissue    into the circulatory system via the walls thereof.

It has been explained above that cancerous cells which do not havefunctional VGSCs expressed therein do not behave invasively. Further, itis known that current passes through VGSCs in pulses, each of whichcomprises a transient or peak part followed by a much lower levelpersistent or late part. In accordance with an aspect of the invention,one or more of the above metastatic behaviours is inhibited or reducedby inhibiting or reducing the persistent part of the current whilst noteliminating the peak part, so making it possible to use a drug whichwill preferentially reduce the persistent part of the current.

Some such drugs are known for treating heart conditions such asarrhythmia or angina. In the case of treating the heart, it is vital toensure that the peak part of the current is not eliminated because thisis essential to maintain the functionality of the heart and its rhythm.Thus, in accordance with an aspect of the invention a known drug, suchas ranolazine or riluzole, previously used for inhibiting or reducingthe persistent part of the VGSC current without eliminating the peakpart is used for inhibiting or reducing metastatic behaviour in cancer,especially breast or prostate cancer.

The nature of the VGSC current, and the effect on it of treatment withranolazine or riluzole, will be further described with reference toFIGS. 3( a), 3(b) and 3(c).

Referring to FIG. 3( a), curve 301, shown as an unbroken line,represents a current pulse flowing through functional VGSC undernormoxic conditions, the horizontal axis being time and the verticalaxis being amplitude or magnitude of the current. As can be seen, thiscurrent pulse comprises a peak or transient portion 302 and thepersistent or late portion 303. In practice, the time period for whichthe persistent part 303 persists is very much greater than the timeperiod of the transient part 302 although, since FIG. 3( a) is adiagrammatic sketch rather than a curve actually obtained fromexperimental data, this is not shown in the figure.

Curve 304, drawn in chain dotted lines, shows a pulse of VGSC currentunder hypoxic conditions. As can be seen, the peak part 305 of thecurrent under hypoxic conditions is smaller than the peak part 301 undernormoxic conditions, but the persistent part 306 under hypoxicconditions is greater than the persistent part 303 under normoxicconditions. The difference between these curves under hypoxic andnormoxic conditions is relevant, as will become clear from considerationof experimental results which are described below, because many of thecells in a cancerous tumour are hypoxic due to their partial isolation,by other cancerous cells, from the blood circulation system.

FIG. 3( b) is a sketch illustrating the effect of increasing doses ofranolazine on the transient and persistent parts of the VGSC currentrespectively. As can be seen, the horizontal axis represents the dosagelevel of ranolazine and the vertical axis represents the normalised VGSCcurrent. Solid line curve 305 represents the magnitude of the transientpart of the current plotted against increasing dosage and broken linecurve 306 represents the magnitude of the persistent part of the currentagainst increasing dosage of ranolazine, dosage levels being indicatedon the horizontal axis.

It can be further seen from FIG. 3( b) that at dosage levels in therange 1 to 10 μM, which are therapeutically acceptable to human beings,the persistent part of the current is reduced significantly more thanthe transient part. The difference between the two reductions isindicated in FIG. 3( b) by the double headed arrows 307.

A similar effect with increasing doses of riluzole can be seen from FIG.3( c), in which solid line curve 308 represents the magnitude of thetransient part of the current plotted against increasing doses ofriluzole and the broken line curve 310 represents the magnitude of thepersistent part of the current. Therapeutically acceptable doses ofriluzole for human beings include the range from 1 μM to 10 μM. As canbe seen in FIG. 3( c), and as represented by double headed arrow 311,the reduction in the magnitude of the persistent part of the current issubstantially more than the reduction in the magnitude of the transientpart.

As with FIG. 3( a), the curves of FIGS. 3( b) and 3(c) are sketches toillustrate the currents rather than being based upon the specificexperimental results.

Experiments which are fully described below have been conducted tomeasure the effects of various dosage levels of ranolazine and riluzoleon one or more of the metastatic behaviours of certain cancerous celllines. Specifically, in these experiments measurements of one or more ofthe adhesiveness of the cells, their lateral mobility, theirinvasiveness and their transverse migration have been made for each ofthese drugs at various dosage levels. Further, experiments have beenconducted to determine the effect of some of these doses on theproliferative activity of the cells and on the viability of the cells(that is to say whether or not the drugs kill the cells).

Before describing the experiments and the quantitative results obtainedfrom them, the following tables summarise qualitatively the resultswhich have been obtained. It can be seen from these tables, and thesubsequent detailed discussion of the experiments and the resultsobtained, that reduction in various metastatic behaviours can beachieved at therapeutically acceptable levels without affecting theproliferation of the cells and without killing the cells. The latter maybe particularly important because it has recently been suggested thattreating cancer by killing the cells may be counter-productive because,after the killing treatment has been discontinued, the cancer mayreappear in more aggressive form. Preventing or reducing theinvasiveness of the cancerous cells without killing them may thereforebe a treatment which has considerable advantages over the conventionaltreatments of killing the cells.

Tables 1 and 2 summarise the results of experiments with various dosagelevels of ranolazine on human breast cancer and rat prostate cancercells (rat prostate cells being similar to human prostate cells). Tables3 and 4 summarise the results obtained by treating cells of the samecell lines with various dosage levels of riluzole.

TABLE 1 BREAST CANCER (HUMAN MDA-MB-231) - RANOLAZINE [μM] CELLBEHAVIOUR Hypoxia Normoxia ADHESION 0.1 μM  1 μM 10 μM 100 μM 0.5 μM  1μM 10 μM  20 μM 100 μM increased increased decreased no benefitincreased increased increased increased increased LATERAL  1 μM 10 μM100 μM  1 μM 10 μM 100 μM MOTILITY decreased decreased decreaseddecreased decreased decreased TRANSVERSE  1 μM 10 μM 100 μM  1 μM 10 μM100 μM MIGRATION decreased decreased decreased increased decreaseddecreased INVASIVENESS  5 μM  10 μM 20 μM 25 μM  50 μM 300 μM 10 μM 20μM  50 μM 300 μM (no pretreatment) no benefit decreased no benefitdecreased decreased decreased decreased decreased no effect decreasedINVASIVENESS  5 μM 25 μM 25 μM (pretreatment) 72 hours 48 hours 72 hoursdecreased decreased decreased PROLIFERA0  1 μM 10 μM 100 μM TION (24hours) no effect no effect no effect CELL  1 μM 10 μM 100 μM VIABILITYno effect no effect no effect

TABLE 2 PROSTATE CANCER (RAT Mat-LyLu) - RANOLAZINE [μM] CELL BEHAVIOURHypoxia Normoxia ADHESION LATERAL MOTILITY TRANSVERSE 20 μM 50 μM 300 μM20 μM 50 μM 300 μM MIGRATION decreased decreased decreased decreaseddecreased no effect INVASIVENESS 20 μM 50 μM 300 μM 20 μM 50 μM 300 μM(no pretreatment) decreased decreased decreased decreased decreaseddecreased INVASIVENESS (pretreatment) PROLIFERATION 20 μM 50 μM 300 μM20 μM 50 μM 300 μM (24 hours) no effect no effect tail off no effect noeffect tail off CELL VIABILITY 20 μM 50 μM 300 μM 20 μM 50 μM 300 μM noeffect no effect no effect no effect no effect no effect

TABLE 3 BREAST CANCER (HUMAN MDA-MB-231) - RILUZOLE [μM] CELL BEHAVIOURHypoxia Normoxia ADHESION LATERAL 1 μM 10 μM 100 μM 1 μM 10 μM 100 μMMOTILITY decreased decreased decreased no effect decreased decreasedTRANSVERSE 1 μM 10 μM 100 μM 1 μM 10 μM 100 μM MIGRATION decreaseddecreased decreased decreased no effect decreased INVASIVENESS 1 μM  5μM 1 μM (no pretreatment) decreased decreased decreased INVASIVENESS  5μM (pretreatment) 72 hours decreased PROLIFERATION 1 μM 10 μM 100 μM (24hours) no effect no effect tail off CELL VIABILITY 1 μM 10 μM 100 μM noeffect cell death cell death

TABLE 4 PROSTATE CANCER (RAT Mat-LyLu) - RILUZOLE [μM] CELL BEHAVIOURHypoxia Normoxia ADHESION LATERAL MOTILITY TRANSVERSE MIGRATIONINVASIVENESS 1 μM 2.5 μM 5 μM 1 μM 2.5 μM 5 μM (no pretreatment)decreased decreased decreased decreased decreased decreased INVASIVENESS(pretreatment) PROLIFERA-   3 μM 5 μM 10 μM 30 μM   3 μM 5 μM 10 μM 30μM TION (24 hours) no effect tail off tail off tail off tail off tailoff tail off tail off CELL 1 μM 10 μM 30 μM 100 μM 10 μM 30 μM 100 μMVIABILITY no effect cell cell cell death no no no death death effecteffect effect

Single-Cell Adhesion Assay

FIG. 4 is a schematic illustration of the single-cell adhesionmeasurement apparatus (SCAMA) first described in the paper by Palmer etal. (2008).

Human breast cancer cells from the MDA-MB-231 cell line were plated at adensity of 2.5×10⁴ cells/ml and left to settle in a cell culture dish401 for 48 hours prior to measurements. Medium was removed and 2 ml ofthe drug under study was applied for 10 minutes. Adhesion was measuredusing a glass micropipette 402 connected to a vacuum pump 403 viaplastic tubing 404. The tip of the micropipette was drawn to about 20 μm(range, 17-24 μm) tip diameter. The vacuum pump was used to createnegative pressure inside a reservoir 405 so that the negative pressurecould be applied to the tip of the micropipette by pressing the thumb tothe open end of a sealable T-piece 406. The cells were observed using a20× microscope objective 407 under the illumination of a lamp 408. Thepressure was measured using a digital manometer 409 connected to acomputer 410 via a RS232 cable 411.

Using a micromanipulator 412, the micropipette 402 was positioned on theperiphery of a single cell. Upon closing of the T-piece 406, thenegative pressure was applied to the cell under investigation and, atthe exact moment that the cell was observed to be detached from theculture dish 401, the pressure was released by opening the T-piece 406.The negative pressure required to detach the cell was recorded on thecomputer as a pressure spike. The peak of the spike (“detachmentnegative pressure” (DNP)) was used as a measure of the cell'sadhesiveness. Using this technique, several recordings could be madefrom a single dish within minutes.

To simulate hypoxic conditions for the cells, hypoxia was chemicallyinduced by application of hydrogen peroxide (1-500 μM) for the final 24hours before testing.

In order to test for the reversibility of a given effect, thepharmacological agent was washed off, fresh medium was added and theplate was incubated for a further 10 minutes prior to re-measurement.Each treatment was carried out on at least two dishes of cells, at least100 cells per dish were measured, and the experiment was repeated threetimes (with corresponding controls).

Lateral Motility Assay

This assay was used to represent the “free” motility of cancer cellsduring local spreading. FIG. 5( a) is a plan view from above of a cellculture dish 501 having a semi-confluent layer of cells 502 on itssurface, the cells being in an aqueous medium 503.

In order to determine lateral motility, a “wound-heal (“scratch”)” testwas carried out, in which a scratch 504 of ˜0.5 mm was made through thelayer of cells, as shown in FIG. 5( b) which is a side sectional view ofthe cell culture dish.

During the period of 24 hours following the formation of the scratch,the cells moved into the gap.

FIGS. 5( c) and 5(d) are schematic plan views of the cell culture dish501 at time t=zero when the width of the scratch 504 is w₀ and time t=24hours when the width of the scratch 504 is w₂₄, respectively.

Transverse Migration Assay

This assay was used to represent the ability of cells to migrate as theyintra/extravasate. FIG. 6 shows a schematic side sectional view of amigration chamber 601 having a Transwell® insert 602 separating thechamber into two sections which, for convenience, will be referred to asthe upper 603 and lower 604 sections of the chamber. The insert 602 hasa migration filter membrane 605 in its base with 8 μm pores 606extending therethrough.

Cells 607 were plated at a density of 2×10⁴/ml on the filter membrane605 and placed under a growth medium 608 containing 1% foetal bovineserum (FBS). A chemotactic gradient was created across the filtermembrane 605 by placing growth medium 609 containing 10% FBS in thelower section 604 of the chamber.

Cells were allowed to migrate across the filter membrane 605 over aperiod of 24 hours, cells migrating and adhering to the underside of thefilter membrane 605.

At the end of each assay, non-migrated cells were removed from the uppersurface of the insert 602 with two different swabs

The number of cells migrating to the underside of the insert 602 wasdetermined using crystal violet staining. Migrated cells were fixed for15 minutes with ice-cold methanol. Then 0.5% crystal violet (in 25%methanol) was added for 15 minutes. The inserts were swabbed again andthen washed in water and allowed to dry. Cells were then counted usingtwelve separate fields of view per insert (×200 magnification).

Invasion Assay

This assay is an extension of the transverse migration assay describedabove. To “invade”, the cells need both (i) to move as in the transversemigration assay and (ii) secrete a proteolytic enzyme to digest theirsurroundings. The ability of cells to invade neighbouring tissues byenzyme secretion was therefore assessed by using a layer of Matrigel™(BD Biosciences) spread across the porous membrane of a Transwell®insert. Matrigel™ is composed of laminin, collagen IV, nidogen/enactinand proteoglycan—a composition comparable to basement membrane proteins.

FIG. 7 is a schematic side sectional view of an invasion chamber 701having a Transwell® insert 702 separating the chamber into upper 703 andlower 704 sections. The insert 702 has a migration filter membrane 705in its base with 8 μm pores 706 extending therethrough. A layer 707 ofMatrigel™ is shown coating the filter membrane 705.

Cells 708 were plated at a density of 2×10⁴/ml onto the Matrigel™ layer707 in 24-well plates (Becton-Dickinson) according to the manufacturers'instructions. 50 μl Matrigel™ was seeded at a 1:7 dilution (10 mg/mlstock) onto the inserts and left overnight. Prior to seeding with thecells the Matrigel™ was rehydrated using medium with no additions. Thismedium was removed prior to seeding the cells.

Cells were plated in a 1-5% FBS chemotactic gradient overnight (12hours). The nutrient concentration in the medium 709 in the uppersection 703 of the chamber was less than the concentration of nutrientin the medium 710 in the lower section 704 to induced movement of thecells through the Matrigel™ layer 707 and through the pores 706 to theunderside of the filter membrane 705. At the end of each assay,non-invaded/non-migrated cells were removed from the upper surface ofthe insert 702 with two different swabs.

The number of cells invading to the underside of the insert 702 wasdetermined using crystal violet staining. Invaded cells were fixed for15 minutes with ice-cold methanol. Then 0.5% crystal violet (in 25%methanol) was added for 15 minutes. The inserts were swabbed again andthen washed in water and allowed to dry. Cells were then counted usingtwelve separate fields of view per insert (×200 magnification). If thedifference in the average number of cells invading the two controlinserts was more than 40%, the experiment was rejected.

Cell Viability Assay

Cells were seeded at a density of 5×10⁴ cells/ml in 35 mm Falcon tissueculture dishes. After treatment with a given drug, the medium wasremoved and replaced with 800 μl of growth medium and 200 μl 0.4% trypanblue (Sigma, Dorset, UK) and incubated for 10 minutes in the incubator.The trypan blue was removed and the cells were washed once with 3 mlgrowth medium. For each treatment, cells from 30 random fields of viewwere counted under 100× magnification. The number of dead cells, stainedblue, was counted in each field of view. The data were expressed aspercentages of living cells out of the total number of cells in givenfields of view. The percentages were averaged and differences betweencontrol and treatment were compared from at least three independentexperiments.

Cell Growth (Proliferation) Assay

Cells were plated at 2×10⁴ cells/ml in 24-well plates (Becton-Dickinson)and allowed to settle overnight. The cells were then treated for therequired time of incubation (24 hours +), with medium changes every 24hours. At the end of the treatment, the medium was removed, and this wasfollowed by the colorimetric3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide (MTT) assay(Grimes et al., 1995). Briefly, 0.1 ml MTT (5 mg/ml made up in thegrowth medium) and 0.4 ml growth medium was added in each well and theplate was incubated for 3-4 hours at 37° C. The medium was then removedfrom the chambers and replaced with 0.5 ml dimethyl sulfoxide (DMSO) and0.063 ml glycine buffer (0.1 M glycine and 0.1 M NaCl; pH 10.5).Absorbance at 570 nm was determined 15 minutes after the addition of theglycine buffer. Results were calculated as means of nine repeats of eachof the treatment vs. control spectrophotometer readings from individualinvasion wells.

Tissue Culture

Experiments were carried out on two strongly metastatic cell lines:

-   -   (i) human metastatic breast cancer MDA-MB-231, and    -   (ii) rat strongly metastatic prostate cancer Mat-LyLu.

Cells were cultured using known methods (e.g. Grimes et al., 1995;Fraser et al., 2005).

Normoxic and Hypoxic Conditions

With the exception of single cell adhesion tests, which are discussed inthe following paragraph, experiments were carried out under either;

-   (i) normal normoxic conditions (95% oxygen, 5% carbon dioxide), or-   (ii) following 24 hours hypoxic pre-treatment (2% O₂, 5% CO₂, 93%    N₂) continued during the assays.

In the single cell adhesion experiments, hypoxia was induced chemicallyby application of hydrogen peroxide (1-500 μM) for 24 hours.

EXAMPLES Example 1 Effects of Chemical Hypoxia on the Single-CellAdhesion of MDA-MB-231 Cells

Chemical hypoxia was induced by treating cells with differentconcentrations of hydrogen peroxide for 24 hours. Single-cell adhesionwas measured using the technique described above and illustrated in FIG.4. The change in detachment negative pressure (ΔDNP) was expressed as apercentage versus a control population of untreated cells. Hypoxiareduced the cell adhesion and increasing the concentration of hydrogenperoxide, i.e., increasing the degree of hypoxia, led to greaterreduction in cell adhesion as shown in FIG. 8. In this figure, thevertical axis represents the change in detachment negative pressure(ΔDNP), increasing downwardly so that a higher negative value isindicative of a cell's lower adhesion and, hence, its tendency todetachment. The horizontal axis is a logarithmic scale of hydrogenperoxide concentration, increasing from left to right.

Human breast cancer cells from the MDA-MB-231 cell line were plated in acell culture dish at a density of 2.5×10⁴ cells/ml and left to settlefor 48 hours prior to measurements. The cells were subjected to hydrogenperoxide concentrations of 1 μM, 10 μM and 100 μM and the negativepressure required to detach cells from the bottom of the cell culturedish was measured. At each concentration of hydrogen peroxide,measurements were taken on at least two dishes of cells for at least 100cells per dish. The experiment was repeated three times and themeasurements of detachment negative pressure are presented in FIG. 8 asmeans±SEM.

In FIG. 8, the data point 801 shows that cells exposed to hydrogenperoxide at a concentration of 1 μM had a mean detachment negativepressure of approximately −9%, data point 802 shows that cells exposedto hydrogen peroxide at a concentration of 10 μM had a mean detachmentnegative pressure of approximately −14%, and data point 803 shows thatcells exposed to hydrogen peroxide at a concentration of 100 μM had amean detachment negative pressure of approximately −20%. Hence,increasing the concentration of hydrogen peroxide decreased the adhesionof the cells and made them easier to detach. In other words, increasingthe severity of the hypoxic conditions led to an increase in thedetachability of the cells.

Example 2 Effects of Ranolazine on the Single-Cell Adhesion ofMDA-MB-231 Cells Under Normoxic and Hypoxic Conditions

Single-cell adhesion was measured using the technique described aboveand illustrated in FIG. 4 for human MDA-MB-231 cells exposed todifferent concentrations of ranolazine and under normoxic and hypoxicconditions. Ranolazine increased the substrate adhesion of cells undernormoxia in a dose dependent manner. The dose-dependent increase in theadhesion of cells was even more marked under hypoxia—See FIG. 9. In thisfigure, the vertical axis represents a measure of the adhesion of cells.The horizontal axis is a logarithmic scale of ranolazine concentration,increasing from left to right. Data were collected from n=7 independentexperiments for each condition and are presented in FIG. 9 as means±SEM.

Human breast cancer cells from the MDA-MB-231 cell line were plated incell culture dishes at a density of 2.5×10⁴ cells/ml and left to settlefor 48 hours prior to measurements.

In the normoxia experiments (curve 901), different dishes of the platedcells were treated with ranolazine at concentrations of 0.1 μM, 0.5 μM,1 μM, 10 μM, 20 μM and 100 μM. At the lowest concentration of 0.1 μM,ranolazine had no effect on the adhesion of the cells. At concentrationsof 0.5 μM, 1 μM, 10 μM, 20 μM and 100 μM of Ranolazine, the adhesionincreased in a dose dependent manner; the amount of increase in adhesionappeared to level off at a concentration of 100 μM Ranolazine.

In the hypoxia experiments (curve 902), hypoxia was chemically inducedby treating the cells with hydrogen peroxide (50 μmol) for 24 hours.Different dishes of the plated cells were treated with ranolazine atconcentrations of 0.1 μM μM, 10 μM and 100 μM Even at the lowestconcentration of 0.1 μM ranolazine the adhesion of the hypoxic cells andthe adhesion increased and continued to increase in a dose dependentmanner for concentrations of Ranolazine of 1 μM 10 μM and 100 μM Theamount of increase in adhesion appeared to level off at a concentrationof 100 μM. Ranolazine and the curves for normoxic and hypoxicexperiments appeared to converge at around this concentration.

From a comparison of the effects of ranolazine on adhesion of cellsunder normoxia (curve 901) and hypoxia (curve 902), the effect ofranolazine was approximately 10-fold greater in hypoxia beforeconvergence at the higher drug concentrations.

Example 3 Effects of Ranolazine on the Lateral Motility of MDA-MB-231Cells Under Normoxia and Hypoxia

Lateral motility of the cells was measured using the technique describedabove and illustrated in FIG. 5.

Referring to FIG. 10, the vertical axis represents the motility index ofthe measured cells, with a reference point for normal motility beingrepresented by the control sample (block 1001 of the histogram) ofMDA-MB-231 cells under normoxia and without drug, normalised to 100%.Across the horizontal axis, the set of results for experiments conductedunder normoxia is plotted on the left-hand side and the set of resultsfor experiments conducted under hypoxia is plotted on the right-handside. For each set of results, the concentration of ranolazine usedincreases from left to right.

Block 1005 is the result obtained for the control sample (without drug)for MDA-MB-231 cells under conditions of hypoxia. From a comparison ofblocks 1001 and 1005 it can be seen that hypoxia increased motility.

Human breast cancer cells from the MDA-MB-231 cell line were treatedwith different concentrations of ranolazine under normoxia, and hypoxia.In the normoxia experiments, the motility of the cells was measuredafter treating them with no drug (control) and ranolazine atconcentrations of 1 μM, 10 μM and 100 μM. The results are shown in FIG.10 as blocks 1001, 1002, 1003 and 1004, respectively. Increasing theconcentration of ranolazine reduced the lateral motility of the cells,but only the reduction at a concentration of 100 μM ranolazine wasstatistically significant.

Similarly, in the hypoxia experiments, the motility of the cells wasmeasured after treating them with no drug (control) and ranolazine atconcentrations of 1 μM, 10 μM and 100 μM. The results are shown in FIG.10 as blocks 1005, 1006, 1007 and 1008, respectively. Increasing theconcentration of ranolazine reduced the lateral motility of the cellsand each concentration of ranolazine tested gave a statisticallysignificant reduction in lateral motility of the cells.

Data were collected from n=3 independent experiments for each conditionand are presented as means±SEM. (*) indicates significance at P<0.05;(**) indicates significance at P<0.01.

Example 4 Effects of Ranolazine on the Transverse Migration ofMDA-MB-231 Cells Under Normoxia and Hypoxia

Transverse migration of the cells was measured using the techniquedescribed above and illustrated in FIG. 6.

Referring to FIG. 11, the vertical axis represents relative values fortransverse migration of the measured cells, with a reference point fornormal transverse migration being represented by the control sample(block 1101) of MDA-MB-231 cells under normoxia and without drug,normalised to 100%. Across the horizontal axis, the set of results forexperiments conducted under normoxia is plotted on the left-hand sideand the set of results for experiments conducted under hypoxia isplotted on the right-hand side. For each set of results, theconcentration of ranolazine used increases from left to right.

Block 1105 is the result obtained for the control sample (without drug)for MDA-MB-231 cells under conditions of hypoxia. From a comparison ofblocks 1101 and 1105 it can be seen that hypoxia increased transversemigration.

Human breast cancer cells from the MDA-MB-231 cell line were treatedwith different concentrations of ranolazine under normoxia, and hypoxia.In the normoxia experiments, the migration of the cells was measuredafter treating them with no drug (control) and ranolazine atconcentrations of 1 μM, 10 μM and 100 μM. The results are shown in FIG.11 as blocks 1101, 1102, 1103 and 1104, respectively. Increasing theconcentration of ranolazine reduced the transverse migration of thecells only slightly and the results were not statistically significant.

In the hypoxia experiments, the migration of the cells was measuredafter treating them with no drug (control) and ranolazine atconcentrations of 1 μM, 10 μM and 100 μM. The results are shown in FIG.10 as blocks 1105, 1106, 1107 and 1108, respectively. Ranolazine atconcentrations of 1 μM and 10 μM reduced the transverse migration of thecells in a statistically significant way; ranolazine at a concentrationof 100 μM also reduced the transverse migration of the cells, but thereduction was not statistically significant.

Data were obtaining from n=3 independent experiments for each conditionand are presented as means±SEM. (*) indicates significance at P<0.05.

Example 5 Effects of Ranolazine on the Invasiveness of MDA-MB-231 CellsUnder Normoxia and Hypoxia (No Pre-Treatment)

The invasiveness of the cells was measured using the technique describedabove and illustrated in FIG. 7.

Referring to FIG. 12, the vertical axis represents relative values forinvasiveness of the measured cells, with a reference point for normalinvasiveness being represented by the control sample (block 1201) ofMDA-MB-231 cells under normoxia and without drug, normalised to 100%.Across the horizontal axis, the set of results for experiments conductedunder normoxia is plotted on the left-hand side and the set of resultsfor experiments conducted under hypoxia is plotted on the right-handside. For each set of results, the concentration of ranolazine usedincreases from left to right.

FIG. 12 also includes results for an additional pair of controls,labelled in the drawing as blocks 1202 and 1208. In these additionalcontrols, cells were exposed to the toxin tetrodotoxin (TTX) whosebinding site is located at the pore opening of the VGSC. The TTXmeasurement is a positive control confirming that sodium channelactivity is indeed contributing (potentiating) the metastatic cellbehaviour under investigation. It should be noted that, at theconcentrations of TTX used here (10 μmol), blocking of the VGSC is nottotal. Hence, particularly at the higher concentrations tested, the drug(ranolazine) appears to be more potent than the toxin (TTX).

Block 1207 is the result obtained for the control sample (without drug)for MDA-MB-231 cells under conditions of hypoxia. From a comparison ofblocks 1201 and 1207 it can be seen that hypoxia increased invasiveness.

Human breast cancer cells from the MDA-MB-231 cell line were treatedwith different concentrations of ranolazine under normoxia, and hypoxia.In the normoxia experiments, the invasiveness of the cells was measuredafter treating them with no drug (control) and ranolazine atconcentrations of 10 μM, 20 μM, 50 μM and 300 μM. The results are shownin FIG. 12 as blocks 1201, 1203, 1204, 1205 and 1206, respectively.Treatment with ranolazine reduced the migration of the cells atconcentrations of 10 μM, 20 μM and 300 μM, but the effect of ranolazineat a concentration of 50 μM was not statistically significant.

In the hypoxia experiments, the migration of the cells was measuredafter treating them with no drug (control) and ranolazine atconcentrations of 5 μM, 10 μM, 20 μM, 50 μM and 300 μM. The results areshown in FIG. 12 as blocks 1207, 1209, 1210, 1211, 1212 and 1213,respectively. Treatment with ranolazine reduced the migration of thecells at concentrations of 20 μM, 50 μM and 300 μM, but the effect ofranolazine at concentrations of 5 μM and 10 μM was not statisticallysignificant.

Data were collected from n=3 independent experiments for each conditionand are presented as means±SEM. (*) indicates significance at P<0.05;(**) indicates significance at P<0.01.

Example 6 Effects of Ranolazine on the Invasiveness of MDA-MB-231 CellsUnder Normoxia and Hypoxia with Pre-Treatment of the Cells

As the reduction in invasiveness at low concentrations of ranolazineunder hypoxia was not statistically significant, a modified version ofthe invasiveness assay was carried out in which the cells werepre-treated with ranolazine for different periods in comparison tocorresponding control conditions (i.e., no ranolazine applied).

FIGS. 13( a) and (b) show the effect of 5 μM ranolazine (ran) oninvasion of MDA-MB-231 cells under conditions of hypoxia in vitro. Thehistograms indicate the number of MDA-MB-231 cells invading followingtreatment with 5 μM ranolazine for different periods in comparison tocorresponding control conditions (i.e. no ranolazine applied).

In FIG. 13( a), block 1301 represents the invasiveness result obtainedunder control conditions (no drug) for cells invading over the 24 hourduration of the assay (i.e., effectively no pre-treatment was used).Block 1302 represents the invasiveness result for cells treated with 5μM ranolazine and invading over the 24 hour duration of the assay (nopre-treatment). The effect on invasiveness of cells treated with 5 μMranolazine was not statistically significant.

In FIG. 13( b), block 1303 represents the invasiveness result obtainedunder control conditions (no drug) for cells invading over the 24 hourduration of the assay (i.e., effectively no pre-treatment was used).Block 1304 represents the invasiveness result for cells pre-treated with5 μM ranolazine for 72 hours and invading over the 24 hour duration ofthe assay. There was a very significant reduction in the invasiveness ofcells pre-treated with 5 μM ranolazine for 72 hours.

In each of FIGS. 13( a) and (b), the number of “cells invading” denotesthe average of cell number counted in 24 randomly chosen fields of viewfrom two separate inserts (experiments).

FIG. 13( c) to (e) show the effect of 25 μM ranolazine (ran) on invasionof MDA-MB-231 cells under conditions of hypoxia in vitro. The histogramsindicate the number of MDA-MB-231 cells invading following treatmentwith 25 μM ranolazine for different periods in comparison tocorresponding control conditions (i.e. no ranolazine applied).

In FIG. 13( c), block 1305 represents the invasiveness result obtainedunder control conditions (no drug) for cells invading over the 24 hourduration of the assay (i.e., effectively no pre-treatment was used).Block 1306 represents the invasiveness result for cells treated with 25μM ranolazine and invading over the 24 hour duration of the assay (nopre-treatment). Cells treated with 5 μM ranolazine were less invasivethan untreated cells in a statistically significant way.

In FIG. 13( d), block 1307 represents the invasiveness result obtainedunder control conditions for cells maintained for 24 hours without drugand invading over the following 24 hours prior to measurement. Block1308 represents the invasiveness result for cells pre-treated for 24hours with 25 μM ranolazine and invading over the following 24 hoursprior to measurement. Cells pre-treated with 25 μM ranolazine for 24hours before commencing the 24 hour long assay were significantly lessinvasive than untreated cells.

In FIG. 13( e), block 1309 represents the invasiveness result obtainedunder control conditions for cells maintained for 48 hours without drugand invading over the following 24 hours prior to measurement. Block1310 represents the invasiveness result for cells pre-treated for 48hours with 25 μM ranolazine and invading over the following 24 hoursprior to measurement. Cells pre-treated with 25 μM ranolazine for 48hours before commencing the 24 hour long assay were again significantlyless invasive than untreated cells.

As above, the number of “cells invading” in the histograms of FIGS. 13(c) to (e) denotes the average of cell number counted in 24 randomlychosen fields of view from two separate experiments.

At both the concentrations tested (5 μM and 25 μmol, pre-treatment ofthe cells with ranolazine led to a statistically significant reductionin their invasiveness. Such pre-treatment of the cells with the drug inan in vitro test is considered to be representative of in vivotreatment, where the patient receives a continual therapeutic dose ofthe drug.

Example 7 Effects of Ranolazine on the Growth of MDA-MB-231 Cells UnderNormoxia and Hypoxia

The growth of the cells was measured using the technique described aboveunder the heading “Cell growth (proliferation) assay”.

Referring to FIG. 14, the vertical axis represents the total cell numberin a plated sample, with reference points for normal growth beingrepresented by the control samples (blocks 1401, 1405 and 1409) ofMDA-MB-231 cells under normoxia and without drug at commencement, after24 hours and after 48 hours, respectively. Across the horizontal axis,three sets of results are shown for measurements taken at commencement,after 24 hours and after 48 hours of growth. Here, the term “growth”includes cell proliferation and cell death and in this assay, both withand without drug, there was an overall increase in the number of cellsover time. For each of the three sets of results, the concentration ofranolazine used increases from left to right.

Human breast cancer cells from the MDA-MB-231 cell line were treatedwith different concentrations of ranolazine under normoxia.

At commencement (0 hours), the number of cells was measured aftertreating them with no drug (control) and ranolazine at concentrations of1 μM, 10 μM and 100 μM. The results are shown in FIG. 14 as blocks 1401,1402, 1403 at 1404, respectively. Increasing the concentration ofranolazine had no effect upon the cell number at commencement.

After 24 hours, the number of cells at each concentration of ranolazinewas counted again. The results are shown in FIG. 14 as blocks 1405,1406, 1407 and 1408. There was no significant difference between thenumber of cells in control sample (block 1405) and the numbers of cellsin the samples treated with ranolazine at concentrations of 1 μM, 10 μMand 100 μM (blocks 1406, 1407 and 1408, respectively).

After a further 24 hours (48 hours in total), the number of cells ateach concentration of ranolazine was counted again. The results areshown in FIG. 14 as blocks 1409, 1410, 1411 and 4012. There was nostatistically significant difference between the number of cells incontrol sample (block 1409) and the numbers of cells in the samplestreated with ranolazine at concentrations of 1 μM, 10 μM and 100 μM(blocks 1410, 1411 and 4012, respectively).

Similarly, in the hypoxia experiments, the motility of the cells wasmeasured after treating them with no drug (control) and ranolazine atconcentrations of 1 μM, 10 μM and 100 μM. The results are shown in FIG.10 as blocks 1005, 1006, 1007 and 1008, respectively. Increasing theconcentration of ranolazine reduced the lateral motility of the cells,with the result that each concentration of ranolazine beingstatistically significant.

Data were collected from n=3 independent experiments for each conditionand are presented as means±SEM.

The same concentrations of ranolazine under hypoxia also did not affectthe growth of the MDA-MB-231 cells (results not shown in FIG. 14).

Example 8 Effects of Ranolazine on the Viability of MDA-MB-231 CellsUnder Normoxia

The viability of the cells was measured using the technique describedabove under the heading “Cell viability assay”.

Referring to FIG. 15, the vertical axis represents the relativeviability of cells in a plated sample, with a reference point for normalviability being represented by the control sample (block 1501) ofMDA-MB-231 cells under normoxia and without drug. The concentration ofranolazine with which different samples of the cells were treated isplotted across the horizontal axis, increasing from left to right.

Human breast cancer cells from the MDA-MB-231 cell line were treatedwith different concentrations of ranolazine under normoxia. Theviability of the cells was measured after treating them for 48 hourswith no drug (control) and ranolazine at concentrations of 1 μM, 10 μMand 100 μM. the results are shown in FIG. 15 as blocks 1501, 1502, 1503and 1504, respectively. There was no effect of ranolazine on cellviability.

Data were collected from n=3 independent experiments for each conditionand are presented as means±SEM.

Example 9 Effects of Ranolazine on Transverse Migration of Mat-LyLuCells Under Normoxia and Hypoxia

Transverse migration of the cells was measured using the techniquedescribed above and illustrated in FIG. 6.

Referring to FIG. 16, the vertical axis represents relative values fortransverse migration of the measured cells, with a reference point fornormal transverse migration being represented by the control sample(block 1601) of Mat-LyLu cells under normoxia and without drug,normalised to 100%. Across the horizontal axis, the set of results forexperiments conducted under normoxia is plotted on the left-hand sideand the set of results for experiments conducted under hypoxia isplotted on the right-hand side. For each set of results, theconcentration of ranolazine used increases from left to right.

FIG. 16 also includes results for an additional pair of controls,labelled in the drawing as blocks 1602 and 1607. In these additionalcontrols, cells were exposed to the toxin tetrodotoxin (TTX) whosebinding site is located at the pore opening of the VGSC. The TTXmeasurement is a positive control confirming that sodium channelactivity is indeed contributing to (potentiating) the metastatic cellbehaviour under investigation. It should be noted that, at theconcentrations of TTX used here (1 μmol), blocking of the VGSC is nottotal. Hence, particularly at the higher concentrations tested, the drug(ranolazine) appears to be more potent than the toxin (TTX).

Block 1606 is the result obtained for the control sample (without drug)for Mat-LyLu cells under conditions of hypoxia. From a comparison ofblocks 1601 and 1606 it can be seen that hypoxia increased transversemigration.

Rat prostate cancer cells from the Mat-LyLu cell line were treated withdifferent concentrations of ranolazine under normoxia, and hypoxia. Inthe normoxia experiments, the migration of the cells was measured aftertreating them with no drug (control) and ranolazine at concentrations of20 μM, 50 μM and 300 μM. The results are shown in FIG. 16 as blocks1601, 1603, 1604 and 1605, respectively. Increasing the concentration ofranolazine reduced the transverse migration of the cells atconcentrations of ranolazine of 20 μM and 50 μM. The effect ofranolazine on transverse migration at a concentration of 300 μM was notstatistically significant.

In the hypoxia experiments, the migration of the cells was measuredafter treating them with no drug (control) and ranolazine atconcentrations of 20 μM, 50 μM and 300 μM. The results are shown in FIG.16 as blocks 1606, 1608, 1609 and 1610, respectively. Ranolazine atconcentrations of 20 μM, 50 μM and 300 μM each reduced the transversemigration of the cells in a statistically significant way.

Data were obtained from n≧3 independent experiments for each conditionand are presented as means±SEM. (*) indicates significance at P<0.05compared to control.

Example 10 Effects of Ranolazine on Invasiveness of Mat-LyLu Cells UnderNormoxia and Hypoxia

The invasiveness of the cells was measured using the technique describedabove and illustrated in FIG. 7.

Referring to FIG. 17, the vertical axis represents relative values forinvasiveness of the measured cells, with a reference point for normalinvasiveness being represented by the control sample (block 1701) ofMat-LyLu cells under normoxia and without drug, normalised to 100%.Across the horizontal axis, the set of results for experiments conductedunder normoxia is plotted on the left-hand side and the set of resultsfor experiments conducted under hypoxia is plotted on the right-handside. For each set of results, the concentration of ranolazine usedincreases from left to right.

FIG. 17 also includes results for an additional pair of controls,labelled in the drawing as blocks 1702 and 1707. In these additionalcontrols, cells were exposed to the toxin tetrodotoxin (TTX) whosebinding site is located at the pore opening of the VGSC. The TTXmeasurement is a positive control confirming that sodium channelactivity is indeed contributing (potentiating) the metastatic cellbehaviour under investigation. It should be noted that, at theconcentrations of TTX used here (1 μM), blocking of the VGSC is nottotal. Hence, particularly at the higher concentrations tested, the drug(ranolazine) appears to be more potent than the toxin (TTX).

Block 1706 is the result obtained for the control sample (without drug)for Mat-LyLu cells under conditions of hypoxia. From a comparison ofblocks 1701 and 1706, it does not appear that hypoxia affected theinvasiveness of the cells. I Rat prostate cancer cells from the Mat-LyLucell line were treated with different concentrations of ranolazine undernormoxia, and hypoxia. In the normoxia experiments, the invasiveness ofthe cells was measured after treating them with no drug (control) andranolazine at concentrations of 20 μM, 50 μM and 300 μM. The results areshown in FIG. 17 as blocks 1701, 1703, 1704 and 1705, respectively.Treatment with ranolazine reduced the migration of the cells in astatistically significant way at each of the tested concentrations ofranolazine.

In the hypoxia experiments, the migration of the cells was measuredafter treating them with no drug (control) and ranolazine atconcentrations of 20 μM, 50 μM and 300 μM. The results are shown in FIG.17 as blocks 1706, 1708, 17091710, respectively. Treatment withranolazine reduced the migration of the cells in a statisticallysignificant way at each of the tested concentrations of ranolazine.

Data were obtained from n≧3 independent experiments for each conditionand are presented as means±SEM. (*) indicates significance at P<0.05compared to normoxia control; (*) indicates significance at P<0.05compared to both normoxia and hypoxia control.

Example 11 Effects of Ranolazine on Growth of Mat-LyLu Cells

The growth of the cells was measured using the technique described aboveunder the heading “Cell growth (proliferation) assay”.

Referring to FIG. 18, the vertical axis represents the total cell numberin a plated sample, with a reference point for normal growth beingrepresented by the control sample (blocks 1801) of Mat-LyLu cells undernormoxia and without drug normalised to 100%. Across the horizontalaxis, the set of results for experiments conducted under normoxia isplotted on the left-hand side and the search of results for experimentsconducted under hypoxia is plotted on the right-hand side. For each setof results, the concentration of ranolazine used increases from left toright. Note that the term “growth” includes cell proliferation and celldeath.

Rack prostate cancer cells from the Mat-LyLu cell line were treated withdifferent concentrations of ranolazine under normoxia, and hypoxia. Inthe normoxia experiments, the number of cells was measured aftertreating them for 24 hours with no drug (control) and ranolazine atconcentrations of 20 μM, 50 μM and 300 μM. The results are shown in FIG.18 as blocks 1801, 1802, 1803 and 1804, respectively. Increasing theconcentration of ranolazine did not result in any statisticallysignificant effect on the number of cells.

Similarly, in the hypoxia experiments, the number of cells was measuredafter treating them for 24 hours with no drug (control) and ranolazineat concentrations of 20 μM, 50 μM and 300 μM. The results are shown inFIG. 18 as blocks 1805, 1806, 1807 and 1808, respectively. Increasingthe concentration of ranolazine did not result in any statisticallysignificant effect on the number of cells at concentrations ofranolazine of 20 μM and 50 μM. At a concentration of ranolazine of 300μM, there was a reduction in the number of cells.

In summary, growth of Mat-LyLu cells was unchanged in all conditionstested except with 300 μM ranolazine under hypoxia Data were collectedfrom n=3 independent experiments for each condition and are presented asmeans±SEM. (*) indicates significance at P<0.05 compared to bothnormoxia and hypoxia control, while (x) indicates no statisticaldifference.

Example 12 Effects of Ranolazine on Viability of Mat-LyLu Cells

Cells were treated with different concentrations of ranolazine at [20μM], [50 μM] and [300 μM] for 24 hours under normoxic or hypoxic (2% O2)conditions. The results obtained are shown in FIG. 19. There was noeffect of ranolazine on cell viability regardless of concentration andregardless of whether the cells were under normoxic or hypoxicconditions. Data were collected from n=3 independent experiments foreach condition and are presented as means±SEM.

Example 13 Effects of Riluzole on the Lateral Motility of MDA-MB-231Cells Under Normoxia and Hypoxia

Lateral motility of the cells was measured using the technique describedabove and illustrated in FIG. 5. Referring to FIG. 20, block 2001 of thehistogram shows the motility index for the control sample of MDA-MB-231cells under normoxia and without drug, normalised to 100%. Block 2005 isthe corresponding control sample (without drug) for MDA-MB-231 cellsunder conditions of hypoxia. From a comparison of blocks 2001 and 2005it can be seen that hypoxia increased motility significantly.

Cells were treated with different concentrations of riluzole ([1 μM],[10 μM], and [100 μM]) under normoxia, and hypoxia. Increasing theconcentration of riluzole reduced the lateral motility of the cells; theeffect was greater under hypoxia. Data were collected from n=5independent experiments for each condition and are presented asmeans±SEM. (*) indicates significance at P<0.05; (**) indicatessignificance at P<0.01.

Example 14 Effects of Riluzole on the Transverse Migration of MDA-MB-231Cells Under Normoxia and Hypoxia

Transverse migration of the cells was measured using the techniquedescribed above and illustrated in FIG. 6. Referring to FIG. 21, block2101 represents the proportion of transverse migration observed for thecontrol sample of MDA-MB-231 cells under normoxia and without drug,normalised to 100%. Block 2105 is the corresponding control sample(without drug) for MDA-MB-231 cells under conditions of hypoxia. From acomparison of blocks 2101 and 2105, it appeared that hypoxia increasedtransverse migration but the increase was not statistically significantfor the number of test runs completed.

Cells were treated with different concentrations of riluzole ([1 μM],[10 μM], and [100 μM]) under normoxia, and hypoxia. Under normoxia,treatment with riluzole reduced the transverse migration of the cells ina statistically significant way at concentrations of 1 μM and 100 μM.Under hypoxia, increasing the concentration of riluzole reduced thetransverse migration in a statistically significant way. Data wereobtaining from n=3 independent experiments for each condition and arepresented as means±SEM. (*) indicates significance at P<0.05.

Example 15 Effects of Riluzole on the Invasiveness of MDA-MB-231 CellsUnder Normoxia and Hypoxia (No Pre-Treatment)

The invasiveness of the cells was measured using the technique describedabove and illustrated in FIG. 7. Results are shown in FIG. 22. Riluzoleat a concentration of 5 μM significantly inhibited invasiveness evenwithout pre-treatment. The number of “cells invading” denotes theaverage of cell number counted in 24 randomly chosen fields of view fromtwo separate inserts (experiments).

Example 16 Effects of Riluzole on the Invasiveness of MDA-MB-231 CellsUnder Normoxia and Hypoxia (72 Hours Pre-Treatment)

The invasiveness of the cells was measured using the same technique asdescribed above for Example 6 with the cells being pre-treated for 72hours with riluzole at a concentration of 5 μM. Results are shown inFIG. 23. Cells pre-treated with riluzole for 72 hours at a concentrationof 5 μM also showed significantly inhibited invasiveness. As above, thenumber of “cells invading” denotes the average of cell number counted in24 randomly chosen fields of view from two separate inserts.

Example 18 Effects of Riluzole on the Growth of MDA-MB-231 Cells UnderNormoxia and Hypoxia

Cells were treated with different concentrations of riluzole at [1 μM],[10 μM] and [100 μM] for 48 hours. The results obtained are shown inFIG. 24. Riluzole at a concentration of 100 μM reduced the proliferationof the cells in a statistically significant way at 24 hours and after 48hours. Data were collected from n=3 independent experiments for eachcondition and are presented as means±SEM. (*) indicates significantlevel at P<0.05.

Example 19 Effects of Riluzole on the Viability of MDA-MB-231 CellsUnder Normoxia and Hypoxia

Cells were treated with different concentrations of riluzole at [1 μM],[10 μM] and [100 μM] for 48 hours. The results obtained are shown inFIG. 25. Riluzole at concentrations of 10 μM and 100 μM decreased thecell viability. Data were collected from n=3 independent experiments foreach condition and are presented as means±SEM. (*) indicates significantlevel at P<0.05.

The same concentrations of ranolazine under hypoxia also did not affectthe growth of the MDA-MB-231 cells (results not shown in FIG. 25).

Example 20 Effects of Riluzole on Matrigel™ Invasion of Mat-LyLu CellsUnder Normoxia and Hypoxia (No Pre-Treatment)

The invasiveness of the cells was measured using the technique describedabove and illustrated in FIG. 7. Referring to FIG. 26, block 2601 showsthe invasion index for the control sample of Mat-LyLu cells undernormoxia and without drug, normalised to 100%. Block 2604 is thecorresponding control sample (without drug) for Mat-LyLu cells underconditions of hypoxia. From a comparison of blocks 2601 and 2604 it canbe seen that hypoxia increased invasion in a statistically significantway.

Riluzole at a concentration of 1 μM significantly inhibited invasivenessunder normoxia and hypoxia even without pre-treatment. Data wereobtained from n≧3 independent experiments for each condition and arepresented as means±SEM. (*) indicates significance at P<0.05 compared tocontrol.

Example 21 Effects of Riluzole on Growth of Mat-LyLu Cells

Cells were treated with different concentrations of riluzole at [3 μM],[5 μM], [10 μM] and [30 μM] for 24 hours under normoxic or hypoxic (2%O₂) conditions. The results obtained are shown in FIG. 27. Riluzoledecreased cell proliferation dose dependently under both normoxia andhypoxia; the effect was greater under hypoxia. Data were collected fromn=3 independent experiments for each condition and are presented asmeans±SEM. (*) indicates significance at P<0.05 compared to control; (x)indicates no statistical difference.

Example 22 Effects of Riluzole on Viability of Mat-LyLu Cells

Cells were treated with different concentrations of riluzole at [10 μM],[30 μM], and [100 μM] for 24 h under normoxic or hypoxic (2% O₂)conditions. The results are shown in FIG. 28. There was no effect ofriluzole (10-100 μM) on cell viability. Data were collected from n=3independent experiments for each condition and are presented asmeans±SEM.

Although the invention has been described mainly in relation toranolazine and riluzole, other substances having the effect of reducingthe persistent VGSC current without eliminating the transient currentmay be used, for example valporate, flecainide, lidocaine, mexiletine orF15845.

Further, although the invention has been described mainly in relation tobreast and prostate cancer, it is applicable to all metastatic cancerswhich express voltage gated sodium channels.

REFERENCES

-   Fraser S P, Diss J K J, Chioni A-M, Mycielska M E, Pan H, Yamaci R,    Pani F, Siwy Z, Krasowska M, Grzywna Z, Brackenbury W J, Theodorou    D, Koyutrk M, Kaya H, Battaloglu E, De Bella M T, Slade M J,    Tolhurst R, Palmieri C, Jiang J, Latchman D S, Coombes R C & Djamgoz    M B A (2005). Voltage-gated sodium channel expression and    potentiation of human breast cancer metastasis. Clin Cancer Res. 11:    5381-5389.-   Grimes J A, Fraser S P, Stephens G J, Downing J E G, Laniado M E,    Foster C S, Abel P D & Djamgoz M B A (1995). Differential expression    of voltage-activated Na⁺ currents in two prostatic tumour cell    lines: contribution to invasiveness in vitro. FEBS Letters 369:    290-294.-   Palmer C P, Mycielska M E, Burcu H, Osman K, Collins T, Beckerman R,    Perrett R, Johnson H, Aydar E & Djamgoz M B A (2008). Single cell    adhesion measuring apparatus (SCAMA): application to cancer cell    lines of different metastatic potential and voltage-gated Na⁺    channel expression. Eur Biophys J. 37: 359-368.

1. Ranolazine for reducing or preventing metastatic behaviour in VGSCexpressing cancer.
 2. Ranolazine according to claim 1, wherein thecancer is breast cancer.
 3. Ranolazine according to claim 1, wherein thecancer is prostate cancer.
 4. Riluzole for reducing or preventingmetastatic behaviour in VGSC expressing cancer without directly killingthe cancer cells.
 5. Riluzole according to claim 4, wherein the canceris breast cancer.
 6. Riluzole according to claim 4, wherein the canceris prostate cancer.
 7. A substance for reducing or preventing metastaticbehaviour in VGSC expressing cancer by the effect of at least reducingthe persistent part of the voltage gated sodium channel current withouteliminating the transient part.
 8. A substance according to claim 7,having said effect in breast cancer.
 9. A substance according to claim7, having said effect in prostate cancer.
 10. A substance according toclaim 7, having said effect without killing the cells.
 11. A substanceaccording to claim 7, having said effect without substantially affectingproliferation.
 12. Ranolazine according to claim 1, in a dosage levelcorresponding to the range 1 μmol to 10 μmol.
 13. Riluzole according toclaim 4, in a dosage level corresponding to the range 1 μmol of 10 μmol.14. A method of reducing or preventing metastatic behaviour in VGSCexpressing cancer comprising administering ranolazine.
 15. A methodaccording to claim 14, wherein the cancer is breast cancer.
 16. A methodaccording to claim 14, wherein the cancer is prostate cancer.
 17. Amethod of reducing or preventing metastatic behaviour in VGSC expressingcancer, comprising administering riluzole without directly killing thecancer cells.
 18. A method according to claim 17, wherein the cancer isbreast cancer.
 19. A method according to claim 17, wherein the cancer isprostate cancer.
 20. A method of reducing or preventing metastaticbehaviour in VGSC expressing cancer by administering a drug having theeffect of at least reducing the persistent part of the voltage gatedsodium channel current without eliminating the transient part.
 21. Amethod according to claim 20, wherein the cancer is breast cancer.
 22. Amethod according to claim 20, wherein the cancer is prostate cancer. 23.A method according to claim 20, carried out without killing the cells.24. A method according to claim 20, carried out without substantiallyaffecting proliferation.
 25. The method according to claim 13, whereinthe ranolazine is administered in a dosage level corresponding to therange 1 μmol to 10 μmol.
 26. A method according to claim 17, wherein theriluzole is administered in a dosage level corresponding to the range 1μmol of 10 μmol.